Hot-pressing preparation method for hexagonal boron nitride-added silicon nitride

A technology of hexagonal boron nitride and silicon nitride, which is applied in the field of ceramic material preparation, can solve the problems of high brittleness and hardness of pure silicon nitride ceramic materials, hidden concerns about quality and safety, and crater wear, etc., and achieve the effect of improving tribological performance.

Inactive Publication Date: 2015-11-11
SHAANXI UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, pure silicon nitride ceramic materials will limit their engineering applications due to high brittleness and hardness. At the same time, pure silicon nitride ceramic materials have a high friction coefficient and wear rate when rubbing under the condition of no medium lubrication, especially with metal parts. When paired, its friction coefficient is as high as 0.4-0.9, and the wear rate is greater than 10 -6 mm 3 / N·m
Consistent with this situation, silicon nitride (Si 3 N 4 )Ceramic tools are prone to crater wear and micro chipping during dry cutting, with a chipping rate of 2% to 3%, causing quality and safety concerns

Method used

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  • Hot-pressing preparation method for hexagonal boron nitride-added silicon nitride
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  • Hot-pressing preparation method for hexagonal boron nitride-added silicon nitride

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Step 1: Use an electronic balance to weigh 70% of silicon nitride, 20% of hexagonal boron nitride and 10% of sintering aid powder in proportion by volume, and place the weighed powder in a ball mill tank for ball milling, Pour in alcohol, the amount added is 1 / 2 of the weight of the material, adjust the viscosity of the fluid, use a planetary ball mill to make it fully mixed, and the ball milling speed is 150r·min -1 , the ball milling time is about 5h;

[0024] Step 2: Put the ball-milled powder in an oven, heat and evaporate to dryness, stir while evaporating until all the alcohol is lost, and prevent agglomeration at the same time, grind the dried mixture, and sieve it with a 160-mesh sieve ;

[0025] Step 3: Put graphite paper with a thickness of 0.2mm around the mold to facilitate demoulding, put the powder into the mold and pre-press it into a biscuit, place the biscuit in a vacuum carbon tube furnace, and under the protection of nitrogen, in the Under the condi...

Embodiment 2

[0040] Step 1: Use an electronic balance to weigh 60% of silicon nitride, 30% of hexagonal boron nitride and 10% of sintering aid powder in proportion by volume, and place the weighed powder in a ball mill tank for ball milling, Pour in alcohol, the amount added is 1 / 2 of the weight of the material, adjust the viscosity of the fluid, use a planetary ball mill to make it fully mixed, and the ball milling speed is 150r·min -1 , the ball milling time is about 5.5h;

[0041] Step 2: Put the ball-milled powder in an oven, heat and evaporate to dryness, stir while evaporating until all the alcohol is lost, and prevent agglomeration at the same time, grind the dried mixture, and sieve it with a 160-mesh sieve ;

[0042] Step 3: Put graphite paper with a thickness of 0.2mm around the mold to facilitate demoulding, put the powder into the mold and pre-press it into a biscuit, place the biscuit in a vacuum carbon tube furnace, and under the protection of nitrogen, in the Under the con...

Embodiment 3

[0052] Step 1: Use an electronic balance to weigh 80% of silicon nitride, 10% of hexagonal boron nitride and 10% of sintering aid powder in proportion by volume, and place the weighed powder in a ball mill tank for ball milling, Pour in alcohol, the amount added is 1 / 2 of the weight of the material, adjust the viscosity of the fluid, use a planetary ball mill to make it fully mixed, and the ball milling speed is 150r·min -1 , the ball milling time is about 6h;

[0053] Step 2: Put the ball-milled powder in an oven, heat and evaporate to dryness, stir while evaporating until all the alcohol is lost, and prevent agglomeration at the same time, grind the dried mixture, and sieve it with a 160-mesh sieve ;

[0054] Step 3: Put graphite paper with a thickness of 0.2mm around the mold to facilitate demoulding, put the powder into the mold and pre-press it into a biscuit, place the biscuit in a vacuum carbon tube furnace, and under the protection of nitrogen, in the Under the condi...

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Abstract

The invention relates to a hot-pressing preparation method for hexagonal boron nitride-added silicon nitride. The preparation method comprises the following steps: adding hexagonal boron nitride having a laminar structure as a solid lubricating agent to silicon nitride, and mixing; meanwhile, adding a sintering aid and carrying out ball grinding; pouring alcohol to adjust the viscosity of fluid; then putting the ball-ground powder to a drying oven, heating, drying by steaming and sieving; then loading the powder to a die, and pre-pressing to form a biscuit; carrying out temperature preservation and pressure preservation in a vacuum carbon tube furnace; finally, reducing the temperature of the vacuum carbon tube furnace to room temperature, and taking sintered silicon nitride composite ceramic out. According to the preparation method disclosed by the invention, boron-containing oxides and hydroxides are generated by means of a chemical reaction between the hexagonal boron nitride and water molecules, so that the siding surface of a material has a lubricating property per se, and thus the tribological property of the silicon nitride ceramic material is remarkably improved, namely the friction factor of the silicon nitride ceramic material is remarkably reduced; the silicon nitride composite ceramic produced by hot-pressing sintering has the characteristics of good self-lubricating and tribological properties and can meet the using demands in actual engineering.

Description

technical field [0001] The invention relates to the technical field of preparation of ceramic materials, in particular to a hot-press preparation method of adding hexagonal boron nitride to silicon nitride. Background technique [0002] Silicon nitride (Si 3 N 4 ) Ceramic materials are widely used in engineering because of their excellent physical and mechanical properties. Among ceramic materials, silicon nitride has a small thermal expansion coefficient, so it has good thermal shock resistance, and its normal temperature resistivity is relatively high, up to 10 13 ~10 14 Ω·cm, can be used as a better insulating material; silicon nitride has good chemical stability, and is resistant to corrosion by all inorganic acids except hydrofluoric acid and some alkali solutions, and is not affected by lead, aluminum, tin, silver, yellow Copper, nickel and other molten metal alloys are infiltrated and corroded. The silicon oxide film formed on the surface can hinder further oxidat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/596C04B35/593C04B35/622
Inventor 陈威吕政琳
Owner SHAANXI UNIV OF SCI & TECH
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